computer network attack. Actions taken through the use of computer networks to disrupt,deny, degrade, or destroy information resident in computers and computer networks, or the computers and networks themselves. Also called CNA. computer network defense. Actions taken through the use of computer networks to protect, monitor, analyze, detect and respond to unauthorized activity within Department of Defense information systems and computer networks. Also called CND. computer network exploitation. Enabling operations and intelligence collection capabilities conducted through the use of computer networks to gather data from target or adversary automated information systems or networks. Also called CNE.

from AFDD 2-5 [descriptions below are abbreviated]

Network warfare operations (NW Ops) Network warfare operations (NW Ops) are the integration of the military capabilities of network attack (NetA), network defense (NetD), and network warfare support (NS). The integrated planning and employment of network warfare operations along with electronic
warfare operations (EW Ops), influence operations, and other military capabilities are conducted to achieve desired effects across the information domain. Network warfare operations, when employed with other information operations, ensure our forces operate in a protected information.

Network attack (NetA) is employment of network-based capabilities to destroy, disrupt, corrupt, or usurp information resident in or transiting through networks. Networks include telephony and data services networks.
Network defense (NetD) is employment of network-based capabilities to defend friendly information resident in or transiting through networks against adversary efforts to destroy, disrupt, corrupt, or usurp it.
Network warfare support (NS) is the collection and production of network related data for immediate decisions involving NW Ops. NS is critical to NetA and NetD actions to find, fix, track, and assess both adversaries and friendly sources of access and vulnerability for the purpose of immediate defense, threat prediction and recognition, targeting, access and technique development, planning, and execution in NW Ops.

The Commander, Joint Functional Component Command Network Warfare is dual-hatted as Director, National Security Agency. This component facilitates cooperative engagement with other national entities in computer network defense and offensive information warfare as part of the global information operations mission. This coordinated approach to information operations involves two other important supporting commands. The Director, Defense Information Systems Agency also heads the Joint Task Force for Global Network Operations. This organization is responsible for operating and defending U.S. worldwide information networks, a function closely aligned with the efforts of the Joint Functional Component Command for Network Warfare. [from Stratcom organization page]

The Joint Task Force-Global Network Operations (JTF-GNO) directs the operation and defense of the Global Information Grid to assure timely and secure Net-Centric capabilities across strategic, operational, and tactical boundaries in support of DoD's full spectrum of war fighting, intelligence, and business missions.